Simple Graphical Method for Locating the End Point of a pH or a Potentiometric Titration.

1966 ◽  
Vol 38 (1) ◽  
pp. 158-158 ◽  
Author(s):  
S. R. Cohen
Keyword(s):  
Potentiometric Titration ◽  
Graphical Method ◽  
End Point

Conductimetric and potentiometric investigation of effect of acidity on formation of homoconjugates in acetonitrile solvent

1990 ◽  
Vol 68 (5) ◽  
pp. 674-678 ◽  
Author(s):  
Turgut Gündüz ◽  
Esma Kiliç ◽  
Güleren Özkan ◽  
Muhammed F. Awaad ◽  
Mustafa Tastekin
Keyword(s):  
Carboxylic Acids ◽  
Potentiometric Titration ◽  
Major Part ◽  
Nitrogen Atmosphere ◽  
Nonaqueous Media ◽  
Potentiometric Titrations ◽  
End Point ◽  
Titration Curves ◽  
Aliphatic Carboxylic Acids ◽  
Conjugate Base

In the present work, 11 aromatic and nine aliphatic carboxylic acids, namely benzoic, 2-nitrobenzoic, 3-nitrobenzoic, 4-nitrobenzoic, 2,4-dinitrobenzoic, 3,5-dinitrobenzoic, 2-aminobenzoic, 3-aminobenzoic, 4-aminobenzoic, o-phthalic, salicylic, formic, acetic, monochloroacetic, dichloroacetic, trichloroacetic, propionic, n-butyric, caprylic, and myristic acids, were titrated conductimetrically and potentiometrically with triethylamine in acetonitrile solvent, under a nitrogen atmosphere, at 25 °C. Closer investigation of the conductimetric titration curves of these acids showed that the acidity of an acid, rather than the basicity of its conjugate base, plays a major part in the formation of homoconjugate ions, at least in acetonitrile solvent. If the acid is strong enough, there is a maximum before the experimental end point at about the half-neutralization point. To determine the minimum strength for an acid to show this maximum before the end point, all acids were also titrated potentiometrically. It was found that those acids which have half-neutralization potentials over −85 mV give a strong homoconjugation reaction and show a maximum before the experimental end point. Moreover, the acids that show maxima before the experimental end point in the conductimetric titration also show rather well-shaped potentiometric titration curves. Keywords: nonaqueous media, conductimetric titrations, potentiometric titrations, titration in acetonitrile, acidity and homoconjugation.

Direct Potentiometric Titration of Urea with Urease

1976 ◽  
Vol 59 (5) ◽  
pp. 1045-1047
Author(s):  
J Harold Falls ◽  
William R Barnacascel ◽  
Perry W Britt
Keyword(s):  
Carbon Dioxide ◽  
Potentiometric Titration ◽  
Ammonium Carbonate ◽  
Break Point ◽  
End Point ◽  
Modified Method ◽  
Back Titration ◽  
Aoac Method ◽  
Titration Step

Abstract AOAC method 2.070–2.071 for determining urea with urease was shown to yield varying results according to the analyst’s interpretation of titrating to a neutral end point. The method was modified to allow the end point of the titration to correspond to the break point of ammonium carbonate (pH 4.2), which is the compound being titrated in the urea analysis. This modified method proved to be a more accurate means of urea analysis. The AOAC method was further modified and simplified by eliminating the back-titration step. Ammonium carbonate may be titrated directly to pH 4.2 without over-acidifying to eliminate carbon dioxide.

THE POTENTIOMETRIC TITRATION OF CARBONATE SOLUTIONS CONTAINING URANIUM

1953 ◽  
Vol 31 (8) ◽  
pp. 705-709 ◽  
Author(s):  
J. Halpern
Keyword(s):  
Hydrochloric Acid ◽  
Potentiometric Titration ◽  
Sodium Carbonate ◽  
Uranyl Nitrate ◽  
Carbonic Acid ◽  
Potentiometric Titrations ◽  
End Point ◽  
Carbonate Solutions ◽  
Hydrolysis Of ◽  
Complex Ion

Potentiometric titrations with hydrochloric acid were carried out on standard sodium carbonate solutions containing varying amounts of uranyl nitrate. The results confirmed the fact that uranium is present in such solutions as the complex ion [Formula: see text]. It was found that only the free CO3−− is titrated with H+ up to the first end point at pH = 8. 2. The complex ion is very stable and is decomposed only on further addition of acid when the complexed CO3−− along with the HCO3− in the solution is converted to carbonic acid before the second end point. The pH at which the second end point occurs is lowered from its normal value of 4.0 in the presence of uranium. This effect is attributed to hydrolysis of the UO2++ ion. The necessary corrections for determining carbonate and bicarbonate in the presence of uranium are given.

Sign in / Sign up

Export Citation Format

Share Document